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Uranium extraction from seawater has attracted worldwide attention due to the massive reserves of uranium. Due to the straightforward synthesis and strong affinity toward uranyl ions (UO22+), the amidoxime group shows promise for use in highly efficient uranium capture. However, the low mass transfer efficiency within traditional amidoxime‐based adsorbents severely limits the adsorption rate and the utilization of adsorption sites. In this work, a macroporous polyamidoxime (PAO) hydrogel is prepared by yeast‐based biological foaming combined with ice crystal dispersion that effectively maintained the yeast activity. The yeast‐raised PAO (Y‐PAO) adsorbent has numerous bubble‐like holes with an average pore diameter >100 µm. These macropores connected with the intrinsic micropores of PAO to construct efficient diffusion channels for UO22+ provided fast mass transporting channels, leading to the sufficient exposure of hidden binding sites. The maximum adsorption capacity of Y‐PAO membrane reached 10.07 mg‐U/g‐ads, ≈1.54 times higher than that of the control sample. It took only eight days for Y‐PAO to reach the saturation adsorption capacity of the control PAO (6.47 mg‐U/g‐ads, 28 days). Meanwhile, Y‐PAO possessed excellent ion selectivity, good reusability, and low cost. Overall, the Y‐PAO membrane is a highly promising adsorbent for use in industrial‐scale uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

• Poly(amidoxime)/Polyzwitterionic adsorbent is fabricated for uranium extraction. • The adsorbent can be easily prepared by free-radical polymerization. • The adsorbent shows high salt shrinkage resistance. • The adsorbent exhibits excellent antibacterial activity. • A high uranium extraction capacity of 6.26 mg g−1 in natural seawater. Effective uranium extraction from seawater can contribute greatly for meeting the needs of low carbon energy. Extensive studies have been conducted on polyamidoxime-based (PAO-based) adsorbents for their exceptional uranium adsorption capabilities. However, the salt-shrinkage effect severely hinders the extraction of uranium from seawater using traditional PAO-based adsorbents. This study synthesizes a novel semi-interpenetrating polymer network hydrogel, designated as PAO/PMPC-SH, using a free-radical polymerization approach utilizing PAO and zwitterionic poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC). The incorporation of the PMPC component endows the adsorbent with exceptional resistance to salt shrinkage owing to the antipolyelectrolyte effect. This characteristic facilitates the diffusion of uranyl ions within PAO/PMPC-SH, even in a high-salt environment with a salt concentration as high as 25 wt%, thereby exposing the uranium binding sites in the adsorbent. Moreover, PAO/PMPC-SH exhibits exceptional antibacterial activity. After 28 days of test in natural seawater, PAO/PMPC-SH demonstrates a high uranium extraction capacity of 6.26 mg g−1, representing only a 9.14 % decrease compared with the capacity of adsorbing in marine microorganism-removed natural seawater. Overall, the notable performance of PAO/PMPC-SH in uranium extraction highlights its potential as a highly effective adsorbent for uranium extraction from seawater. [ABSTRACT FROM AUTHOR]